There are many types and varieties of illuminated signs, some of which have translucent panels with an opaque message with a background which is illuminated by lamps from behind. Others are just opposite wherein light from lamps on the inside shine through transparent or translucent letters or numerals. Some are painted signs illuminated from the front from above or below. One common type of sign is referred to as a box sign because it is in the form of a box with lamps, either inside or on the outside directed toward a front panel carrying its message. Some such signs may carry a message on both sides.
There are some disadvantages to such signs for highway or roadway use because lamps can burn out leaving the sign dark and, in many cases, illegible or illegible at a desired distance. Either incandescent or fluorescent lamps connected to the main power source from an electric utility company may stop working at almost any time either from power outages or burned-out lamps. Replacing of lamps and other servicing of such signs is expensive and time consuming. Dirt and dust are a problem and wiring can be damaged from heavy storms, hail, etc. The amount of electrical energy consumed by such incandescent or fluorescent lamps is also a disadvantage.
There is, therefore, a need for illuminated highway or roadway signs which are more reliable, more effective, and less expensive to operate than signs presently in use.
Light-emitting diodes have been used in some signs as illustrated by U.S. Pat. Nos.:                5,964,051        5,469,347 and        5,388,357        
Solar powered signs are typified by U.S. Pat. No. 4,484,104.